Dicyanoketene cyclic acetals and process for preparation



-class of substituted ketene cyclic acetals.

pounds. scription of the invention given hereinafter.

United States PatentO DICYANOKETENE CYCLIC ACETALS PROCESS FOR PREPARATION Richard Edwin Heckert, Richmond, Va., and William Joseph Middleton, Claymont, Del., assignors to E. I. du Pont de Nemours and Company, Wilmington, DeL, a corporation of Delaware a No Drawing. Filed Apr. 25, 1958, Ser. No.'7so,79s 7'Claims. c1. zen-340.7

AND

those in which the substituents are hydrocarbon are best known. A monocyanoketene acetal has been described -(McElvain, S. M., and Schroeder, J. P., J. Am. Chem. Soc. 71, 47 (1949) but the preparation of higher cyanosubstituted derivatives of ketene cyclic acetals has not been previously accomplished.

An object of the present invention is to provide a new A further object is to provide a process of preparing such com- I Other objects will be apparent from the de- The above objects are accomplished according to the present invention by reacting tetracyanoethylene with .dihydric alcohols to form dicyanoketene cyclic acetals.

The Z-dicyanomethylene-l,3-dioxacycloaliphatic compounds which are obtained are colorless, crystalline .solids melting at temperatures in the range of 50 C.- -150 C. and above. Their preparation from tetracyanoethylene and dihydric alcoholsmay be illustrated as follows:

NO ON where R is a divalent aliphatic hydrocarbon radical with its valences stemming from adjacent carbon atoms or Patented Apr. 18, 1961 minutes until solution is complete. The resulting black reaction mixture is cooled to 0 C. and 250 parts of cold water is added. The precipitate which forms is separated by filtration and recrystallized 3 times from ethanol, using decolorizing carbon. There is obtained 7.1 parts of white crystalline 2-dicyanomethylene-l,3- dioxolane melting at 112-1 14 C.

Example I] A mixture of 64 parts of tetracyanoethylene, 10 parts of urea, and 134 parts of ethylene glycol is heated over a steam bath until the dark color which forms at first, fades. The mixture is cooled and poured into 5000 parts of cold water. The precipitate is collected on a filter (64 parts, 94% yield) and recrystallized from alcohol-water using decolorizing carbon. There is obtained 46.2 parts of Z-dicyanomethylene-1,3-dioxolane,

Example III A mixture of 64 parts of tetracyanoethylene, 10 parts of urea, and 263 parts of trimethylene glycol is heated until all the solid dissolves. The solution is cooled to 0 C., and a precipitate of long, white needles forms.

from carbon atoms separated by a single carbon atom.

and the dicyanoketene cyclic acetal crystallizes out. The

acetal is purified by recrystallization. I

Tetracyanoethylene, for use in the process of the present invention, can be prepared by heating sulfur monochloride with malononitrile, suitably in the presence of an inertliquid diluent.

In the following examples illustrative of the invention, parts are by weight except where otherwise speci- Example I i a I A mixture of 64 parts of tetracyanoethylene and 134 parts of ethylene glycol is heated to boiling for several This precipitate is collected on a filter and washed with water to yield 70 parts (93% yield) of crude product which is then recrystallized from ethyl alcohol. There is obtained 55 parts of Z-dicyanomethyIene-I,3-dioxane, alternately named dicyanoketene trimethylene acetal, in the form of white needles, M.P. 119 C.-120 C. The infrared absorption spectrum shows a doublet band at 4.48 and 4.52 microns for CEN and a band at 6.40 ,microns for --C=C-.

AnaIysis.-Calcd. for C H O N ,C, 56.01; H, 4.03; N, 18.67; M.W., 150. Found: C, 56.13, 55.99; H, 4.28. 4.35; ,N, 18.76, 18.76;. M.W., 151, 145. I,

Example IV v NC/ \OCH2 in the form of a white crystalline solid, M.P. 60 C.-,- 61" C.

AnaIysis.-Calcd. for OzHsOzNzi C, 56,01; H, 4.03;

N, 18.67. Found: C, 55.97, 56.13; H, 4.08, 4.02; N, 18.72, 18.80.

Example V A mixture of 284 parts ,of 3-cyclohexene-1,1-dimethylol, 3256 parts of tetracyanoethylene, 20 parts of urea. and 890 parts of tetrahydrofuran isheated at 6080 C. for about 10 minutes until the solids dissolve. The solu- 3 Ben-1's cooled to roomtemperature and 2000 parts of water is added. The precipitate which forms is collected by filtration, washed with water and recrystallized from ethanol. There is obtained 275 parts of Z-dicycanomethylene-l,=3-'dioxaspiro 5.5]undecene 7,

in the form of white needles 'rneltingatl60 l6l-C.

Analysis.-Calcd. for C12H12N2O2: C, 66.64; H, 5.60; N, 12.96. Found: C, 66.78; H, 5.59; N, 13.07.

It will be understood the above exampleslare merely illustrative and that the present invention broadly comprises the n'ew classof' compounds, dicyanoketene cyclic :acetals, and th'emethod ofpreparing such acetals by reacting tetracyanoethylene'with a glycol.

"As will be apparent to those skilled in the art, any

"member of the class of Y dicyanoketene cyclic acetals "can be pr-epared by selecting the correspondingglycol to react 'with the 'tetracyanoethylene. This .is illustrated in the examples and is-further'illustrated as-follows:

When 3,4-diethyl-3,4 hexanediol (tetraethylethyleneglycol) is employed, '2-dicyanomethylene-4,4,5,S-tetraeth- -yl-1,3-dioxolane is'obtained. 'Whe'n 4,5-octanediol-is employed, Z-dicyanomethylene-4,5-di-n-propyl-1,3-dioxolane is obtained. When Z-inethyl-ZA-peritanediol is employed, 2-dicyanornethylene-4,4,6-trimethyl-1,3 dioxane is obtained. V

The present invention is not restricted to the acetals formed by reacting tetracyanoethylene with glycols, that is, dihydric alcohols. The reaction of this invention is likewise applicable to other polyhydric alcohols, such as cellulose and polyvinyl alcohol. When tetracyanoethyl ene reacts with polyvinyl alcohol, the polyvinyl ketal of beta, beta-dicyanoketene is obtained, in which part or an of thepolyvinyl alcohol moleculeis converted to structures as follows:

CHr-CH-CHz-C H are the acetals of'glycols, i.e., aliphaticsaturated or'unsaturated polyhydric alcohols.

As illustrated in Example I, the reaction oftetracyanoethylene with 1,2 and 1,3 glycols to produce the corresponding Z-dicyanornethylene-1,3-dioxolanes and 'Z-difcyanomethylene-1,3-dioxanes will take place -by "simply bringing the reactants into intimate contact. Heatingaccelerates the reaction but is not essential. The use ofa catalyst likewise accelerates the reaction, and to obtain good yields of product within a reasonable length of time the use of a catalyst is preferred. Catalysts particularly suitable for the purpose include urea, tertiary amines and salts of the metals. 1 There is a great variety in the substances which satis- 'factorily function as catalysts. Not only "arete'rtiary 'amines of all sorts suitable catalysts but the widest assortment of salts of metals are effective. No inoperative metal salt has been found. Suitable catalysts include such materials as-urea, FeCls, CrCla, Mg(OAc)2, CoClz, MnClz, MgClz, 'CuClz, CaClz, AgNOa, Ni C12, 'Cu(OAc)a,

Ce(NH4) (N0a) a, triethylamin'e," and pyridine.

The amount of catalyst employed, if any, may be varied over wide limits. The reaction may be carried out with trace amounts of catalyst (0.1 mole percent) but a concentration of catalyst of l to 50 mole percent based on the tetracyanoethylene is preferred in order to eliminate side reactions and shorten the time necessary for complete reaction. v

The process of the present invention may be carried out at room temperature but to promote more rapid completion of the reaction, it is preferred to use elevated temperatures, particularly those in the range from 50 C. up to the boiling point of the glycol being used to prepare the acetal. As will be seen from'the foregoing examples, this includes temperatures up to 200 C. and above. Pressure is not critical and atmospheric pressure normally will be employed as a matter of convenience.

It is preferred to carry out the process of the present invention in the presence of an excess of the glycol being .used inthe reaction, the excess glycol serving as a. "solvent and diluent. Other solvents and diluents which are inert to the'reactants may be usedif desired. Suitable solvents for this purpose are hydrocarbons, e.g., 'hexane, cyclohexene, benzene, and the like, and the 'ethers, e;g.,dimethyl ether, diethylether, and the like. When an inertsolvent is-employed, only chemical equivalentamounts of'the glycol and tetracyanoethylene need *be employed.

The. dicyanoketene cyclic acetals of this invention are characterized by greater thermal stability than the correspondingnon-cyclic-dialkylacetals. The cyclic acetals are also specifically useful'for reacting with tertiary amines to prepare 2,2- dicyano l [(trisubstitutedammonium)- alkoxy]ethenolates as shownby W. J. Middleton in U.S. 2,721,206-and for reacting with hydrocarbon sulfides,'thioamides and thioureas to prepare'2,2-dicyano l-[(dihydro- 'carbonsulfonium)alkoxy]ethenolates, -2,2 dicyano -.1- '[(acylimidiumthio)alkoxy]ethenolates and 2,2 dicyano- 1-[(S-isothiouronium)alkoxy]ethenolates, respectively, as shown by V. A. Engelhardtand W. J. Middleton in U.S. 2,766,270.

'The cyclic acetals ofthis invention are useful ffor the preparation of-polymeric materials. All of these icompounds possess vinyl unsaturation and can be converted by the action of vinyl type polymerization catalysts to 'the'correspondingvinyl polymers-in which the predomi' 'nant structure is of the type i is? it;

where 'Ris=as'defined above. "These polymers :are thermcw plastic, *gum like products which are'useful as hot-melt adhesives for bookbinding. 'The -high cyano content of these adhesives imparts resistance to mildew, mold, and rot so that these adhesives are particularly useful in bindingbooks and papers to be exposed to high humidi'ties, forexample, in the tropics.

The Z-dicyanomethylene cyclic 1,3-acetalsgsuch as the 'z-dicyanomethylene-l,S-dioxolanes and the 2-dicyanomethylene l, 3-'dioxanes, are especially useful because of their capacity for conversion to crosslinked polymeric form.- 'Thesecomp'ounds possess not only the capacity for vinyl-type polymerization-noted above 'but havethe additional jcapacity for polymerization to polyethers through'ringiopening of'rthe cyclic acetal ring. Thus, vinyl-type polymerization of these products yields a thermoplastic polymer of the, type indicated above which is thencompounded with known ring opening and polymerization 'cata'lysts suitable "for polymerizing the cyclic acetal part of the structure. This composition is then molded under heat and pressure, the heat being sufiicient to activate the ring opening and polymerization catalysts with the resultantformation of crosslinlged structures of the type:

6 es 5 (IN is l ON 4) ON A A A 5 5 N 5 N ft 1L This same crosslinking effect is achieved when the two types of polymerization characteristic of the dicyanoketene cyclic acetals are carried out in reverse order, i.e., the dicyanoketene cyclic acetal is first polymerized through ring opening to yield a thermoplastic dicyanomethylene-substituted polyether. A vinyl-type polymerization catalyst is then incorporated and the composition is molded under heat and pressure to produce a crosslinked, infusible, insoluble molded object. Such moldings are particularly useful as insulators and component parts of electrical heating appliances such as for handles of electric irons and dials and knobs for electrically heated cooking appliances.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

We claim:

1. Z-dicyanomethylene-l,S-dioxolane.

'2. Z-dicyanomethylene-1,3-dioxane.

3. 2-dicyanomethylene-4-methyl-l,3-dioxolane.

4. 2-dicyanomethylenel ,3 -dioxaspiro 5 .5 undecene-7.

5. A compound selected from the class consisting of Z-dicyanomethylene-l,3-dioxolanes of the formula wherein the Rs are selected from the class consisting of hydrogen and lower alkyl, and 2-dicyanomethylene-1,3- dioxanes of the formula wherein the Rs are selected from the class consisting of hydrogen, lower alkyl and R and R taken together represent with the carbon to which they are attached a cyclohexene ring having a double bond in the 3-position. 6. Process for preparing a compound selected from the class consisting of Z-dicyanomethylene-1,3-dioxolanes of the formula R1 Ra HO-'l-I-OH wherein the Rs are selected from the class consisting of hydrogen and allcyl, and 2-dicyanomethylene-L3- dioxanes of the formula 7 no-d-e-o-on J I l 0 wherein the Rs are selected from the class consisting of hydrogen, lower alkyl and R and R taken together represent with the carbon, to which they are attached a cyclohexene ring having a double bond in the 3-position WhlCll comprises heating tetracyanoethylene with a glycol selected from the class consisting of compounds of the formula B! 0-41-13. C=C/ wherein the Rs are selected from the class consisting of hydrogen and lower alkyl, and compounds of the formula 7 NC\ /O /Rs NC O-C R4 wherein the Rs are selected from the class consisting of hydrogen, lower alkyl, and R and R taken together with the carbon to which they are attached represent a cyclohexene ring having a double bond in the 3-position.,

7. Process for preparing a compound selected from the class consisting of Z-dicyanomethylene-l,3-di0xolanes of the formula wherein the Rs are selected from the class consisting of hydrogen and lower alkyl, and 2-dicyanomethylene-1,3-

dioxanes of the formula B R1 No 045 a, NC o-c m the wherein the Rs are selected from the class consisting of hydrogen, lower alkyl, and R and R taken together with the carbon to which they are attached represent a cyclohexene ring having a double bond in the 3-position.

(References on following page) Jlgferences Cited in .ihefile of this patent Y FOREIGN .PATENTS l 1 UNITED STATES JZAIENIS 544.421 Great Britain .Ap.r.,.i1'3, .1942

2,683,659 Schlesinger July 13, 1954 888968 France 1943 2,883,368 Middleton Apr. 21, 1959 5 UNITED STATES PATENT OFFICE Certificate of Correction Patent No. 2,980,698 April 18, 1961 Richard Edwin Heckert et al.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, lines 4 and 5, for Q-dicycanomethylene read 2-dicyanomethylene-; column 3, line 51, for alcoohls read -a1cohols; column 5, lines 71 to 74, the formula should appear as shown below instead of as in the patent:

column 6, lines 3 to 6, the formula should appear as shown below instead of as in the patent:

R1 R9 No 0-4: R3 o=c o NC/ o-c R lines 14 to 19, the formula should appear as shown below instead of as in the patent:

R1 a Ho-o- ':-o11 f1 1'1 same column 6, lines 22 to 28, the formula should appear as shown below instead of as in the patent:

R1 Ra Ra rro-c-o-h-on t,

Signed and sealed this 9th day of January 1962.

[SEAL] Attest ERNEST W. SWIDER, DAVID L. LADD,

Commissioner of Patents. 

5. A COMPOUND SELECTED FROM THE CLASS CONSISTILNG OF 2-DICYANOMETHYLENE-1,3-DOXOLANES OF THE FORMULA 